3 Replies Latest reply: Mar 21, 2013 2:02 AM by Fayn_dba RSS

    Primary Crash

    Fayn_dba
      Dear All Experts;

      We are going to take down our Primary db for maintenance,so users will work on Standby. I have already tested failover which was successful.
      Now the situation is that we are going to increase our SAN storage & Ram in Primary db.

      if for instance my SAN crashes than What I will do to rebuild the Primary. I will be doing the following things

      Backups
      1. I am taking full backup from RMAN including Archivelog
      2. Before shutdown of OS I will take cold backup also (db is down).
      3. Datapump dump

      So How I will resync my primary db with standby, Will RMAN ROLLFORWARD work after restoring cold backup for me in Primary db from standby db?

      Thanks in Advance

      Warm Regards
        • 1. Re: Primary Crash
          Hemant K Chitale
          The datapump dump isn't useful for a primary-standby configuration but it will be your absolute last backup option in case you can't restore the cold backup.

          Just before you shutdown the database for the cold backup, ensure that the last archivelog has been shipped and applied at the standby.

          When you do the cold backup, also backup the online redo logs (this is absolutely contrary to what advice you would normally receive !) Why ? The last CURRENT online redo log that hadn't been archived at the time of the shutdown will be the first one that will be archived after the restore -- and this will be needed by the standby site. If you restore the cold backup without online redo logs, you'd have to OPEN RESETLOGS. That would result in the primary being a separate incarnation and the standby wouldn't apply the subsequent archivelogs from the primary. That is why I suggest that you also get the online redo log and not OPEN RESETLOGS at the primary.

          All of this is just in case your SAN reconfiguration "blows up" your primary database and you have to restore the primary database.



          Hemant K Chitale
          • 2. Re: Primary Crash
            CKPT
            We are going to take down our Primary db for maintenance,so users will work on Standby. I have already tested failover which was successful.
            Now the situation is that we are going to increase our SAN storage & Ram in Primary db.

            if for instance my SAN crashes than What I will do to rebuild the Primary. I will be doing the following things

            Backups
            1. I am taking full backup from RMAN including Archivelog
            2. Before shutdown of OS I will take cold backup also (db is down).
            3. Datapump dump

            So How I will resync my primary db with standby, Will RMAN ROLLFORWARD work after restoring cold backup for me in Primary db from standby db?
            As i understood correctly, In your maintenance of migration of SAN/RAM, users will accessible on new primary after performing failover on standby database.
            So the latest data will be on the new primary database. If you want to sync with the old primary database with the changes. You have to build the standby again and then perform the switchover.

            Because on standby whenever you perform failover, New incarnation started then the old backups will be no more valid even Primary database will be in different incarnation.

            I suggest you to perform the switchover , use the new primary for any changes.
            Once your old primary was ready, then synchronize the old primary with new primary. So that there will be no new incarnations are allowed. Later once synchronized then you can again perform switchover.

            Hope this clears.
            • 3. Re: Primary Crash
              Fayn_dba
              Dear Experts;

              Thankyou very much for your Help & fruitful suggestion.
              Hope my SAN accepts changes

              Warm Regards